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3 years ago

What is the sign of enthalpy change for (a), an endothermic reaction? (b). an exothermic reaction?

Chemistry

1 answer:

fenix001 [56]3 years ago

8 0

Answer:

The answer is: (a) positive; (b) negative.

Explanation:

The change in enthalpy (ΔH) of a reaction is the amount of energy absorbed or released during a chemical reaction carried out at constant pressure.

a) In an endothermic chemical reaction, heat energy is absorbed by the system from the surrounding. Therefore, the sign of enthalpy change for an endothermic process is positive, ΔH= positive.

b) In an exothermic chemical reaction, heat energy is released by the system into the surrounding. Therefore, the sign of enthalpy change for an exothermic process is negative, ΔH= negative.

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An aqueous solution of calcium hydroxide is standardized by titration with a 0.120 M solution of hydrobromic acid. If 16.5 mL of

Artist 52 [7]

<u>Answer:</u> The molarity of calcium hydroxide in the solution is 0.1 M

<u>Explanation:</u>

To calculate the concentration of base, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HBr$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is $Ca(OH)_2$

We are given:

$n_1=1\\M_1=0.120M\\V_1=27.5mL\\n_2=2\\M_2=?M\\V_2=16.5mL$

Putting values in above equation, we get:

$1\times 0.120\times 27.5=2\times M_2\times 16.5\\\\M_2=0.1M$

Hence, the molarity of $Ca(OH)_2$ in the solution is 0.1 M.

7 0

3 years ago

The reaction for photosynthesis producing glucose sugar and oxygen gas is:

uranmaximum [27]

Answer:

a. 1.12 L

Explanation:

Step 1: Write the balanced equation for the photosynthesis

6 CO₂(g) + 6 H₂O(l) ⇒ C₆H₁₂O₆(s) + 6 O₂(g)

Step 2: Calculate the moles corresponding to 2.20 g of CO₂

The molar mass of CO₂ is 44.01 g/mol.

2.20 g × 1 mol/44.01 g = 0.0500 mol

Step 3: Calculate the moles of O₂ produced

The molar ratio of CO₂ to O₂ is 6:6. The moles of O₂ produced are 6/6 × 0.0500 mol = 0.0500 mol

Step 4: Calculate the volume occupied by 0.0500 moles of O₂ at STP

At STP, 1 mole of O₂ occupies 22.4 L.

0.0500 mol × 22.4 L/1 mol = 1.12 L

4 0

2 years ago

The periodic table is based on an element's

Stels [109]

The answer will be B.

4 0

2 years ago

Read 2 more answers

If water were a linear (not bent) molecule like co2, electrostatic interactions between water molecules would be much weaker. wh

Ksenya-84 [330]

Answer;

The partial negative charge on oxygen would stick out less and be less able to participate in hydrogen bonding.

Explanation;

Water is a polar molecule because the electrons are not shared equally, they're closer to the oxygen atom than the hydrogen.

-Normally, the water molecule is a bent shape because of the pair of lone electrons - they repulse each other and exert a compression to the hydrogen atoms at a slight 104º angle. It is a bent molecular geometry that results from tetrahedral electron pair geometry.

-The 2 lone electron pairs exerts a little extra repulsion on the two bonding hydrogen atoms to create a slight compression to a 104 degrees bond angle. Therefore, the water molecule is bent molecular geometry because the lone electron pairs.

Thus, If water were a linear molecule like co2, electrostatic interactions between water molecules would be much weaker, then the partial negative charge on oxygen would stick out less and be less able to participate in hydrogen bonding.

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3 years ago

A 0.15 m solution of chloroacetic acid has a ph of 1.86. What is the value of ka for this acid?

dem82 [27]

Answer: $1.67\times 10^{-3}$